. Fresh-water biology. Freshwater biology. 7o6 FRESH-WATER BIOLOGY 76 (23, 83) Six pairs of feet. Antennules of female large, fixed. Intestine sirople; no ceca. Family Bosminidae Sars . 77 Body short and high often oval or round. Valves cover body and abdomen. Antennules of 9 long, immovably fixed to head. No abdominal process or ocellus. Intestine without convolutions or ceca. Animals small, rarely exceeding mm. 77 (82) Antennules of female approximately parallel to each other, curving backward, fixed to head; olfactory setae on side, usually near base Bosmina Baird 1845 78 Animal usually
. Fresh-water biology. Freshwater biology. 7o6 FRESH-WATER BIOLOGY 76 (23, 83) Six pairs of feet. Antennules of female large, fixed. Intestine sirople; no ceca. Family Bosminidae Sars . 77 Body short and high often oval or round. Valves cover body and abdomen. Antennules of 9 long, immovably fixed to head. No abdominal process or ocellus. Intestine without convolutions or ceca. Animals small, rarely exceeding mm. 77 (82) Antennules of female approximately parallel to each other, curving backward, fixed to head; olfactory setae on side, usually near base Bosmina Baird 1845 78 Animal usually hyaline; valves thin; infero-posteal angle with spine — the mucro. Antennules of 9 immovably fixed to head; olfactory setae on side, with small triangular plate above them; distal position of antennules looks segmented. Antennae with 3- and 4-iointed ramus. Post- abdomen somewhat quadrate; anus terminal; spines small and inconspicuous; claws set on a cyUndrical process. $ smaller than J, with short, blunt rostrum; large free antermules; book and long flagellum on first foot. Little work has been done in this country on this very difficult genus; but it is certain there are not so many species nor so great an amount of variation here as in Europe. 78 (79) Claws with two series of spinules. Bosmina longirostris (O. F. MiiUer) 1785. Two series of spinules on daws, the basal increasing in length distally, contin- ued by very fine denticles to tip of claw. Frontal sense-hair about midway between eye and junction of antermules. Antennules moderate or short (var. brevicornis); sometimes re- curved at apex (var. cor- nula). Transparent or clear yellowish. Length, 9 , mm.; $, mm. Very common and very variable. In open water of lakes, in weedy mar- gins, in pools and Fig. 1096. Bosmina longirostris, typical specimen; p, post-abdomen more highly mugnified. Rostrum; a, var. cornuta: b, var. brevicornis. 79 (78) Claws with basal series of spinules only 8p. Plea
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
